The cornea provides protection for the intraocular contents of the eye and refracts and focuses light onto the retina. Many diseases and conditions can lead to opacity of the cornea, resulting in blindness. These include trauma, infections, inflammation, previous ocular surgery, and genetic conditions.
Keratoplasty, or corneal transplantation, is a surgical procedure where a damaged or diseased cornea is replaced. The replacement material is typically donated corneal tissue from a recently deceased individual, but there is a shortage in the donor tissue available. The replacement corneal tissue has to be obtained from a deceased donor and preserved until the time of transplantation. The tissue has to be harvested within 12 hours of death, and used within approximately seven days. The success rate also depends on the existing underlying condition of the eye.
Up to 10 million people worldwide suffer from blindness or other disorders resulting from corneal dysfunctions. However, only approximately 100,000 conical transplants are performed annually. The disparity in these numbers results directly from a lack of appropriate donor tissue.
Although an artificial cornea would solve the problem of corneal tissue availability and other problems, previous attempts at artificial corneas have had various deficiencies. One challenge of developing an artificial cornea is to design and manufacture a structure that is optically clear centrally and biocompatible peripherally that would allow for cellular integration. This has proven difficult in practice. Artificial corneas that have been implanted in patients have had severe complications, such as endophthalmitis (intraocular infections), extrusion, glaucoma (uncontrolled elevated intraocular pressure), epithelial downgrowth, uveitis (intraocular inflammation) and tissue necrosis. These complications may be partly due to poor tissue adhesion between the keratoprothesis, and the recipient tissue, resulting in severe irreversible loss of vision.
Many synthetic corneas have been used. Synthetic corneas and their production and use are described in, for example, U.S. Pat. No. 6,976,997 to Noolandi et al., U.S. Pat. No. 6,106,552 to Lacombe et al., U.S. Pat. No. 5,108,428 to Capecchi et al., and U.S. Pat. No. 4,693,715 to Abel, Jr., all of which are hereby incorporated by reference.
These replacement corneas suffer from the problems of being expensive or incompatible with many patients. Thus, there still exists a need in the art of corneal replacements for a material that can be made inexpensively and biologically compatible.